(1) Field of the Invention
The present invention relates a method for laminating a substrate, wherein a substrate for reinforcement (for support) is laminated onto various kinds of substrates, such as semiconductor wafers, glass substrates, and wiring boards through a double-sided adhesive sheet, and to an apparatus using the method.
(2) Description of the Related Art
Semiconductor wafers (hereinafter referred to as “wafer”) are obtained in a manner that the back side of the wafer is ground by a back grinding process after formation of a large number of elements on the wafer, and subsequently the wafer is cut into each element in a dicing process. However, as demand for a higher density packaging increases in recent years, a smaller wafer thickness level from 100 micrometers to 50 micrometers, and furthermore a level of approximately 25 micrometers tend to be needed. The wafer that has been subjected to back grinding into such a level of thickness may have possible brittleness and distortion, leading to extremely poor handling property.
Accordingly, a method of reinforcement of the wafer by lamination of a substrate having rigidity such as a glass plate etc. to a wafer through an adhesive sheet has been proposed and is in practical use.
In detail, a wafer having an adhesive tape beforehand applied on the top face thereof is mounted in a holding stand, and a base made of a glass plate etc. (a substrate in the present invention) is held at the upper end of a base supporting section in a slanting attitude over this wafer. In this condition, a press roller is moved to the surface of the base held in a slanting attitude, the base supporting section is lowered corresponding to the movement, thereby laminating the base onto the semiconductor wafer (refer to JP-A No. 2000-349136).
However, since lamination of the wafer to the substrate for reinforcement is performed after beforehand lamination of an adhesive tape to an extremely thin-finished wafer in conventional apparatuses for laminating a base, the function of an external force in lamination of the adhesive tape to the wafer may damage the wafer.
In the case of the lamination to the wafer by pressing with the rolling motion of the press roller on the surface of the base, a pressing force will be applied in a rolling direction of the press roller, resulting in an unexpected gap of the lamination position of a substrate in the rolling direction.